Influence of carbon nanotube length on toxicity to zebrafish embryos

Abstract

There is currently a large difference of opinion in nanotoxicology studies of nanomaterials. There is concern about why some studies have indicated that there is strong toxicity, while others have not. In this study, the length of carbon nanotubes greatly affected their toxicity in zebrafish embryos. Multiwalled carbon nanotubes (MWCNTs) were sonicated in a nitric acid solution for 24 hours and 48 hours. The modified MWCNTs were tested in early developing zebrafish embryo. MWCNTs prepared with the longer sonication time resulted in severe developmental toxicity; however, the shorter sonication time did not induce any obvious toxicity in the tested developing zebrafish embryos. The cellular and molecular changes of the affected zebrafish embryos were studied and the observed phenotypes scored. This study suggests that length plays an important role in the in vivo toxicity of functionalized CNTs. This study will help in furthering the understanding on current differences in toxicity studies of nanomaterials.

Keywords:

• length
• carbon nanotubes
• sonication
• developmental toxicity
• zebrafish

Acknowledgements

The work described in this paper was substantially supported by a grant from the National Natural Science Foundation of China to JP Cheng (grant no 41101489). Prof Ya-ping Sun’s lab and Dr Wing Lin Poon are thanked for experimental assistance.

Disclosure

The authors report no conflicts of interest in this work.

Supplementary figure

Figure S1 Representative transmission electron microscopy graphs of the nucleus of the blastoderm cells of the embryos loaded with FITC-BSA-MWCNTs at one-cell stage (A–E) and untreated control (F) at 6 hpf. Embryos loaded with FITC-BSA-MWCNTs had irregular shape of nucleus and some micro-nucleus structure also appeared in treated embryos (see white arrow in C), while cells of the untreated embryos had regular round or a horse-shoe shaped nucleus at 6 hpf. Scale bar is 1 μm in A, B and C, and 2 μm in D, E and F.

Abbreviations: FITC-BSA-MWCNT, fluorescein isothiocyanate-labeled bovine serum albumin-functionalized multiwalled carbon nanotube; hpf, hours postfertilization.